Power unit for garden appliances and the like

ABSTRACT

A motor unit for driving a machine or tool such as a gardening tool has small stroke internal combustion engine mounted on a tubular frame which has provision for attachment of an extension handle-for example, when using the unit to power a lawnmower. The engine is coupled to an output shaft for power takeoff to the machine or tool by way of transmission means including a speed reducer which is selectively engageable. The tubular frame is provided with rapid attachment means for connection of the motor unit to the machine or tool to be driven.

United States Patent 1 1 3,616,867

[72] Inventor Alfredo Celli [56] References Cited Via Senio, Forli,Italy UNITED STATES PATENTS [211 1 3 1: 1970 2,621,463 12/1952Skillman...... 56/2X 22 g" d 1 2,845,050 7/1958 Wacker e161 173/170x 1 FE F 3 1969 3,012,441 12/1961 Lambetal... 173/163X g 3,156,231 10/1964Harding 173/17ox [31] 51876 A/69; Primary Examiner-David H. Brown A 11,1970, It l No. 68229 A/70 Attorney-Sughrue, Rothwell, Mion, Zinn &Macpeak ABSTRACT: A motor unit for driving a machine or tool such as agardening tool has small stroke internal combustion en- [54] FOR GARDENAPPLIANCES AND gine mounted on a tubular frame which has provision forattachment of an extension handle-for example, when using 6 Claims 11Drawing Figs the unit to power a lawnmower. The engine is coupled to an[52] US. Cl 173/163, output shaft for power takeoff to the machine ortool by way 173/170 of transmission means including a speed reducerwhich is [51] lnt.Cl B27c 3/08 selectively engageable. The tubular frameis provided with [50] Field of Search 173/163, rapid attachment meansfor connection of the motor unit to 170, 171; 77/7; 143/1; 30/122; 56/2the machine or tool to be driven.

PATENTED V 2 l9?! SHEET 2 OF 4 PATENTEUunv 2 lSTl SHEET 3 [1F 4PAIENTEUHUV 2 I971 3,616,867

SHEET '4 OF 4 Fig. 8

POWER UNIT FOR GARDEN APPLIANCES AND THE LIKE This invention relates tomotor units for operating horticultural or agricultural machines ortools.

Motor units for this purpose are known which comprise an internalcombustion engine and means for attachment of the unit to a machine ortool to be operated by the engine.

In general, however, such known units are cumbersome and heavy, and thispresents an obstacle to the extensive practical use of such units,especially where the tool or machine to be operated is of the typedesigned to be held in the hand.

Moreover, such known motor units generally have a single speed ofoperation, and this limits their range of application to particulartypes of tools or machines. In order to extend the range of operation ofsuch units to lower speed tools it is necessary to modify them byfitting appropriate speed reducers, or to fit speed reducers to thetools or machines to be driven.

An object of the present invention is to provide a motor unit of theaforementioned type of relatively reduced size and weight, which is ofsimple and strong construction and practical and easy to use.

A further object of the invention is to provide a motor unit of the saidtype which is capable of rapid attachment to different tools or machinesto be driven.

According to the invention there is provided a motor unit of theaforesaid type, characterized in that the internal combustion engine hasa small piston stroke and is mounted on a tubular support provided withan upper handle and with an attachment for an extension handle, the saidengine being coupled, through selectively engageable speed reducermeans, to an output shaft adapted for power takeoff to the machine ortool, the said tubular support being provided with rapid attachmentmeans for connection of the motor unit to the said machine or tool to beoperated thereby.

The motor unit according to the invention can be used to motorize a widerange of different tools or machines having different operating speeds.

The invention will now be described, by way of nonlimiting example, withreference to the accompanying drawings, in which:

FIG. I is a side elevation of a motor unit according to a preferredembodiment of the invention, shown in a state of detachment fromcooperating parts of a tool to be driven thereby;

FIG. 2 is a diagrammatic transverse cross section taken along the lineII-Il of FIG. 1;

FIG. 3 is a diagrammatic plan view, partly cut away, of the motor unitof FIG. 1;

FIG. 4 is a partial section of the motor unit taken in the verticalplane represented by the line IV-IV in FIG. 3;

FIG. 5 is an axial section of one-half of the speed reducer incorporatedin the motor unit of FIG. 1, sectioned along line V-V of FIG. 3, andshowing a first setting of the speed reducer in which the latter isoperative;

FIG. 6 is an axial section similar to FIG. 5, showing the speed reducerin a second setting in which it is inoperative, and

FIGS. 7 to ill inclusive are diagrammatic plan views showing someexamples of practical applications of the motor unit of the invention.

As shown in FIG. I the motor unit 1 according to the invention has ashaped tubular metal support frame 2 upon which is mounted an internalcombustion engine 9 of small piston displacement. The tubular frame 2has a lower horizontal portion 24 upon which the engine 9 is mounted bymeans of a front fixing lug 6 and a rear lug 8, the latter being boltedto a rear support plate 7 which is in turn bolted to the rear of theengine 9. The tubular frame 2 also includes an upper horizontal portion2b upon the end of which a handgrip 3 is affixed, and, branching fromthe lower portion 2a an upwardly inclined rear tubular attachment 4 towhich a rear tubular extension handle 5 may be fitted in use of themotor unit (FIGS. 7 to l l A fuel tank 53 for supplying fuel to theengine 9 is slung beneath the upper frame portion 2b.

The engine 9 is provided with a centrifugal clutch 10 (FIGS. 3 and 4)which drives a toothed pulley Ill. A flexible toothed transmission belt12 provides a drive connection between the pulley 11 and a similartoothed pulley l3 keyed to one end of an intennediate shaft 14.

The shaft 14 is rotatably and coaxially supported in a tubular casing 15which is attached to the cylinder block of the engine 9 by means ofintermediate lugs 16. The tubular casing 15 is closed at one end by acap 17 in which a bearing for the shaft 14 is supported. At its otherend the casing 15 is closed by a tapered head 18 having a central axialopening through which an output shaft 19 projects. The shaft 19 isdriven by the intermediate shaft 14 and affords a power takeoff pointfor operating tools or machines adapted to be driven by the motor unit1.

One-half of the casing 15 is shown in axial section in FIGS. 5 and 6.The casing 15 houses a speed reducer which can be engaged as required todrive the output shaft 19 with a reduced rotational speed in relation tothat of the intermediate shaft 14. When the speed reducer is not engagedthe output shaft 19 is driven at the same rotational speed as theintermediate shaft 14.

The intennediate shaft 14 has an axially splined end within the casing15 in permanent meshing engagement with a group of toothed planet wheels20. The wheels 20 rotate in planetary motion around the inside of aninternally toothed fixed ring gear 21, the planet wheels 20 beingrotatably mounted on respective pins 22 which are carried by a rotaryplanet carrier. The planet carrier comprises a front plate 23 and a rearplate 24, the latter having a tubular rearward extension 25 projectingaxially towards the head 18. The tubular extension 25 is provided at itsextremity with internal gear teeth 26.

The output shaft 19 is spaced from but coaxial with the intermediateshaft 14. The shaft 19 has an axially splined inner end 19a within thecasing 15, matching the adjoining splined end 14a of the shaft 14. Atubular sleeve 27 is mounted for axial sliding movement on the splinedshaft end 190, being for this purpose formed with internal axial splines29 mating with the splined end 19a. The sleeve 27 has an external row ofgear teeth 28 which, in a first axial position of the sleeve 27 (FIG. 5)meshes with the internal gear teeth 26 of the planet carrier extension25.

In a second axial position of the sleeve 27 (FIG. 6) the internalsplines 29 of the sleeve 27 engage the externally splined and 14a of theintermediate shaft 14, drivingly interconnecting the shafts 14 and 19.

The tubular sleeve 27 is provided at its end opposite the teeth 28 witha pair of annular flanges 30 defining between them an annular channel inwhich one end of a selector lever 31 engages. The selector lever 31 isformed integrally with a radial crankpin 32 which is rotatably supportedin and projects outwardly from an internal boss 33 on the head 18. Aselector control lever 34 is attached to the outwardly projecting end ofthe pin 32: appropriate rocking movement of the lever 34 causes axialmovement of the sleeve 27 between its first and second positions In thefirst operative position of the sleeve 27 (FIG. 5) the teeth 28 areengaged with the teeth 26 of the planet carrier extension 25, while theinternal splines 29' of the sleeve are engaged only with the splined end19a of the output shaft I9. Under these conditions, drive istransmittedifrom the shaft 14 to the output shaft 19 at reduced speedvia the planet wheels 20, the planet carrier 23, 24 and the sleeve 27.

In the second position of the sleeve 27 (FIG. 6) the splined ends 14aand 19a of the respective shafts 14 and 19 are directly interconnectedby their engagement with the internal splines 29 of the sleeve 27, thelatter having been moved to the left from the position shown in FIG. 5to span the adjoining coaxial splined ends 14a, 19a. The external teeth28 of the sleeve 27 are disengaged from the internal teeth 26 of theextension 25 of the planet carrier, and the shaft 14 transmits drivedirect to the output shaft 19 without any change of speed.

It is therefore possible to engage or disengage the speed reducer simplyby manipulation of the control lever 34. This simplifies theconstruction of the motor unit 1 and simplifies the use of the unit,since assembly and disassembly of a speed reducer separate from themotor unit, as has previously been necessary, is avoided.

The lower portion 2a of the tubular support frame 2 is provided withmeans for the rapid attachment of the motor unit 1 to a tool or machineto be driven. Such attachment means, shown in FIGS. 1 and 2, comprise ahook 40 arranged beneath the frame portion 2a adjacent the mounting lug6 and a clamping pin 41 extending through the frame portion 2a andmounted therein for rotation about a lateral horizontal axis spaced fromthe hook 40. The pin 51 is provided at one end with an adjuster nut 42and at the other end with an axially slidable clamping member 43 withwhich a lever arm 44 cooperates. The lever arm 44 is integral with aninternal eccentric cam (not shown) which is effective to displace theclamping member 43 along the pin 41 selectively towards or away from thenut 42 when the lever arm 44 is rocked through 90 The above-describedattachment means cooperate with corresponding attachment means on thetool or machine to be connected to the motor unit 1. Part of atransverse support of the tool is shown at 35: a plate 36 is mounted onthe upper side of the support 35 and has an outwardly projecting edge 37adapted to engage in the hook 40 of the motor unit frame portion 20. Aforked cradle member 36 is mounted on the plate 36 and is adapted toreceive part of the tubular frame portion 2a. The upwardly projectingarms of the forked cradle member 38 are formed with an aligned pair ofvertical slots 39, open at their upper ends, into which the outwardlyprojecting parts of the said transverse pin 41, inwardly of the nut 42and the clamping member 43 may be engaged.

To connect the motor unit 1 to the tool to be driven, it is simplynecessary first to engage the projecting edge 37 of the plate 36 in thehook 40 and thereafter to locate the tubular frame portion 2a in thecradle member 38 with the ends of the pin 41 engaged in the slots 39.The lever arm 44 is then rotated through 90 to the position shown inbroken outline in FIG. 2 to clamp the forked arms of the cradle member38 between the frame portion 2a and the nut 42 and clamping member 43respectively.

Disengagement of the tool from the motor unit 1 is effected by reversingthe operations described above.

The motor unit I as described can be used for driving tools and variousagricultural and horticultural machines, some of which are illustratedin H68. 7 to 11.

ln FIG. 7, the motor unit 1, fitted with the extension handle 5, isdirectly connected to a rotary hoe having radial blades, adapted to beheld in the hand by means of the extension handle 5.

In FIG. 8 the motor unit I is connected to a lawn mower or rotary grasscutter 46 supported on the ground by means of wheels or rollers. Theoutput shaft 19 is fitted with a toothed sprocket for driving the rotarygrass cutter by means of a chain transmission 19 The mower 46 is guidedby means of the extension handle 5.

FIG. 9 illustrates the mounting of the motor unit 1 on a wheeledcarriage 47 which carries a pump 68, directly connected to the outputshaft 19 of the motor unit 1. The pump 48 is connected to a liquid sprayand draws liquid from a storage tank 49 on the carriage 47.

FIG. shows an arrangement similar to that of FIG. 9, in which the motorunit 1 is mounted on a wheeled carriage 47. In this case the motor unit1 drives a centrifugal pump 50 which is driven at high speed byappropriately presetting the speed reducer of the motor unit to achievemaximum output shaft speed.

A further application is illustrated in FIG. 11, in which the motor unit1 is again mounted on a wheeled carriage 47. However, the output shaft19 of the motor unit 1 is in this example connected to a powered hedgetrimmer 52 having a rotary drive input, by way of a flexible drivetransmission 51.

It will be understood that, in addition to those applicationsspecifically described by way of example, the motor unit according tothe invention is capable of numerous other applications where a machineor tool to be driven is provided with means for attachment of the motorunit and means for coupling the drive output of the motor unit to themachine or tool.

What is claimed is:

1. Motor unit for operating a horticultural or agricultural machine ortool, comprising an internal combustion engine and means for attachmentof the unit to a machine or tool to be operated by said engine, whereinthe improvement consists m:

i. a tubular support upon which the internal combustion engine havingpiston stroke, is mounted;

ii. an upper handle (3) and an attachment for an extension handlecarried by the said support;

iii. an output shaft for power takeoff to a machine or tool to beoperated;

iv. transmission means through which the engine is coupled to the outputshaft;

v. speed reducer means;

vi. selector means for selectively inserting the speed reducer means insaid transmission means, and

vii. rapid attachment means on the tubular support for connection of themotor unit to the said machine or tool to be operated thereby.

2. Motor unit as claimed in claim 1, wherein the said transmission meansinclude a centrifugal clutch and a toothed belt drive transmissioncoupling the internal combustion engine to the speed reducer means.

3. Motor unit as claimed in claim 1, wherein the rapid attachment meansfor the connection of a machine or tool to the motor unit comprise ahook provided on a lower portion of the tubular support and adapted toengage a projecting edge of a support plate affixed to the machine ortool, and a clamping pin extending laterally through the said lowerportion of the tubular support and provided with opposed clampingelements adapted to clamp respective arms of a forked member attached toor integral with said support plate of the machine or tool, which armshave respective slots in which the said clamping pin engages.

4. Motor unit as claimed in claim 1, wherein the speed reducer meanscomprise;

i. a tubular casing attached to the engine;

ii. an intermediate shaft extending coaxially into the said casing anddrivingly connected to the engine;

iii. external splines on one end of the said shaft within the casing iv.a planet carrier rotatably mounted within the casing;

v. toothed planet wheels rotatably mounted on the planet carrier, saidplanet wheels being in constant mesh with the external splines on saidshaft;

vi. a fixed internally toothed ring gear meshing with the said planetwheels;

vii. a tubular extension of the planet carrier, said extension havinginternal gear teeth;

viii. an externally splined end of the said output shaft within thecasing and coaxial with the intermediate shaft;

and wherein the said selector means are effective in one position tointerconnect the said end of the output shaft with the planet carrierextension and in another position to connect the output shaft directlywith the intermediate shaft, whereby the output shaft may be driven fromthe intermediate shaft at two different rotational speeds.

5. Motor unit as claimed in claim 4, wherein the said selector meanscomprise an axially slidable tubular sleeve mounted coaxially on andcoupled to the said splined end of the output shaft (19), the saidsleeve having external gear teeth which in a first axial position of thesleeve cooperate with the internal gear teeth of the planet carrierextension, said external gear teeth in a second axial position of thesleeve meshing with the external splines of the said intermediate shaft,whereby in the first position of the sleeve the output shaft is drivenat a different speed from the intermediate shaft by way of the planetgears and planet carrier, and in the second position of the sleeve theoutput shaft is directly driven from the intermediate

1. Motor unit for operating a horticultural or agricultural machine ortool, comprising an internal combustion engine and means for attachmentof the unit to a machine or tool to be operated by said engine, whereinthe improvement consists in: i. a tubular support upon which theinternal combustion engine having piston stroke, is mounted; ii. anupper handle (3) and an attachment for an extension handle carried bythe said support; iii. an output shaft for power takeoff to a machine ortool to be operated; iv. transmission means through which the engine iscoupled to the output shaft; v. speed reducer means; vi. selector meansfor selectively inserting the speed reducer means in said transmissionmeans, and vii. rapid attachment means on the tubular support forconnection of the motor unit to the said machine or tool to be operatedthereby.
 2. Motor unit as claimed in claim 1, wherein the saidtransmission means include a centrifugal clutch and a toothed belt drivetransmission coupling the internal combustion engine to the speedreducer means.
 3. Motor unit as claimed in claim 1, wherein the rapidattachment means for the connection of a machine or tool to the motorunit comprise a hook provided on a lower portion of the tubular supportand adapted to engage a projecting edge of a support plate affixed tothe machine or tool, and a clamping pin extending laterally through thesaid lower portion of the tubular support and provided with opposedclamping elements adapted to clamp respective arms of a forked memberattached to or integral with said support plate of the machine or tool,which arms have respective slots in which the said clamping pin engages.4. Motor unit as claimed in claim 1, wherein the speed reducer meanscomprise; i. a tubular casing attached to the engine; ii. anintermediate shaft extending coaxially into the said casing anddrivingly connected to the engine; iii. external splines on one end ofthe said shaft within the casing iv. a planet caRrier rotatably mountedwithin the casing; v. toothed planet wheels rotatably mounted on theplanet carrier, said planet wheels being in constant mesh with theexternal splines on said shaft; vi. a fixed internally toothed ring gearmeshing with the said planet wheels; vii. a tubular extension of theplanet carrier, said extension having internal gear teeth; viii. anexternally splined end of the said output shaft within the casing andcoaxial with the intermediate shaft; and wherein the said selector meansare effective in one position to interconnect the said end of the outputshaft with the planet carrier extension and in another position toconnect the output shaft directly with the intermediate shaft, wherebythe output shaft may be driven from the intermediate shaft at twodifferent rotational speeds.
 5. Motor unit as claimed in claim 4,wherein the said selector means comprise an axially slidable tubularsleeve mounted coaxially on and coupled to the said splined end of theoutput shaft (19), the said sleeve having external gear teeth which in afirst axial position of the sleeve cooperate with the internal gearteeth of the planet carrier extension, said external gear teeth in asecond axial position of the sleeve meshing with the external splines ofthe said intermediate shaft, whereby in the first position of the sleevethe output shaft is driven at a different speed from the intermediateshaft by way of the planet gears and planet carrier, and in the secondposition of the sleeve the output shaft is directly driven from theintermediate shaft.
 6. Motor unit as claimed in claim 5, including aselector lever arranged to move the tubular sleeve axially between itsfirst and second positions, and a pair of annular flanges on the saidsleeve, the inner end of the selector lever being located between thesaid annular flanges, and an external control lever arranged to displacesaid sleeve by means of the selector lever.